A vibration absorber generally is a device used to reduce vibration in a structure whose motion is undesirable or whose motion is sought to be minimized. Vibration absorbers are commonly used in vehicles, aircraft, and other mechanisms that carry passengers—at least to provide the passengers with a more comfortable ride as well as for other reasons.
A type of vibration absorber referred to as a tuned vibration absorber (TVA) is used in many applications for the suppression of a specific vibration frequency. TVAs are used in many applications because of their relative low cost and well-established vibration absorption capabilities. TVAs, however, suffer the drawbacks of being passive devices and of being effective only for a relatively narrow bandwidth.
Another type of vibration absorber is the active; vibration controller (AVC). An AVC typically includes real-time property-changing characteristics and therefore can be highly effective. But uses of AVCs is vibration control mechanisms have been limited because AVCs have been costly to implement. Another problem that may arise in the use of AVC is that of an AVC adding energy to the system (and possibly driving the system into instability) in the event of an unanticipated excitation or improper control of the AVC.
Thus, there is a need for a vibration absorber that includes the advantages, but does not suffer the drawbacks of the TVAs nor the limitations of the AVCs. There is a need for a vibration absorber that effectively and essentially eliminates vibration in structures and that is available at low cost with well-established vibration absorption capabilities. There is a need for a vibration absorber that may adaptively operate over a frequency range without the problems associated with adding energy to the system. Further, there is a need for a vibration absorber that is lightweight and compact.